This invention relates generally to accelerometers and more particularly to accelerometers including a mass that is resiliently coupled to a housing.
Accelerometers are used to detect and record environmental data. In particular, accelerometers are often used in seismic applications to gather seismic data. Conventional accelerometers typically include mass resiliently coupled to a support structure by one or more resilient L-shaped members. Accelerometers that use an L-shaped resilient member to support a mass typically have difficulty providing a sensor having acceptable closed-loop stability and structural reliability.
The present invention is directed to overcoming one or more of the limitations of the existing accelerometers.
According to one embodiment of the present invention, an accelerometer is provided that includes a measurement mass for detecting acceleration that includes a housing having a cavity, one or more spring mass assemblies positioned within the cavity, and one or more metal electrode patterns coupled to the spring mass assembly. Each spring mass assembly includes a support structure, one or more resilient folded beams coupled to the support structure, and mass coupled to the resilient folded beams. A top cap wafer is coupled to the measurement mass that includes a top capacitor electrode. A bottom cap wafer is also coupled to the measurement mass that includes a bottom capacitor electrode.
According to another embodiment of the present invention, an accelerometer is provided that includes a measurement mass for detecting acceleration that includes a housing having a cavity, one or more spring mass assemblies positioned within the cavity, and one or more metal electrode patterns coupled to the spring mass assembly. Each spring mass assembly includes a support structure, one or more resilient S-shaped beams coupled to the support structure, and mass coupled to the resilient S-shaped beams. A top cap wafer is coupled to the measurement mass that includes a top capacitor electrode. A bottom cap wafer is also coupled to the measurement mass that includes a bottom capacitor electrode.
According to another embodiment of the present invention, an accelerometer is provided that includes a measurement mass for detecting acceleration that includes a housing having a cavity, one or more spring mass assemblies positioned within the cavity, and one or more metal electrode patterns coupled to the spring mass assembly. Each spring mass assembly includes a support structure, one or more resilient straight beams coupled to the support structure, and mass coupled to the resilient straight beams. A top cap wafer is coupled to the measurement mass that includes a top capacitor electrode. A bottom cap wafer is also coupled to the measurement mass that includes a bottom capacitor electrode.
According to another embodiment of the invention, a method of operating an accelerometer having a measurement mass positioned within a housing including top and bottom electrodes positioned between corresponding top and bottom capacitor electrodes is provided that includes resiliently coupling the measurement mass to the housing using a resilient folded beam.
According to another embodiment of the invention, a method of operating an accelerometer having a measurement mass positioned within a housing including top and bottom electrodes positioned between corresponding top and bottom capacitor electrodes is provided that includes resiliently coupling the measurement mass to the housing using a resilient S-shaped beam.
According to another embodiment of the invention, a method of operating an accelerometer having a measurement mass positioned within a housing including top and bottom electrodes positioned between corresponding top and bottom capacitor electrodes is provided that includes resiliently coupling the measurement mass to the housing using a resilient straight beam.
According to another embodiment of the invention, a method of preventing crack propagation in a micro-machined structure including a webbing artifact is provided that includes providing one or more vent holes within the webbing artifact.
According to another embodiment of the invention, a method of minimizing backside etching of elements within a micro-machined structure is provided that includes providing one or more etch-buffers adjacent to the element.
According to another embodiment of the invention, a method of protecting a mass supported within a support structure by one or more springs is provided that includes providing one or more soft-contact bumpers for preventing impacts between the mass and the support structure.
The present embodiments of the invention provide an accelerometer for providing reliable data measurements. The accelerometer includes a measurement mass that is resiliently coupled to a housing by using a folded beam, an S-shaped beam or a straight beam. In this manner, the accelerometer provides low noise as well as low temperature stability. The accelerometer further includes range-of-motion limit stops for limiting motion of the measurement mass in the lateral direction thereby enhancing the cross axis sensitivity and lateral shock tolerance of the accelerometer.